488 LECTURE XIX. 



with very marked leucorrhoea. You saw there no 

 doubt that the cells in leucorrhoea very closely resemble 

 those of epithelium of the part, although they no longer 

 entirely retain the typical form of pavement epithelium. 

 The less, however, they approach in their development 

 the typical forms of the epithelium of the part, the more 

 incapable do they become of performing their functions. 

 They are moveable upon a surface, to which they ought 

 properly to adhere, they flow down* and produce re- 

 sults which are incompatible with the integrity of the 

 parts. 



In the narrower sense of the word heterologous new- 

 formations are no doubt alone destructive. The homo- 

 logous ones may accidentally bee ome veryinjurious, but 

 still they do not possess what can properly be called a 

 destructive (in the unscientific and traditional sense of 

 the word), or malignant character. On the other hand 

 every kind of heterologous formation, whenever it has 

 not its seat in the entirely superficial parts, has a certain 

 degree of malignity clinging to it. And even superficial 

 affections, though entirely confined to the most external 

 layers of epithelium, may gradually exercise a very 

 prejudicial influence. Let us only reflect what happens 

 when a large surface of mucous membrane continually 

 secretes, and heterologous products are constantly engen- 

 dered upon it which do not become persistent epithelium, 

 but continually keep flowing down from the surface of 

 the mucous membrane. In such a case, in addition to 

 the blennorrhoea (and its consequences, ansernia, neural- 

 gia, etc.), we find erosions. 



It seems to me important that I should bring before 

 you a definite example of the mode in which destruction 

 in its more obvious forms is effected, in order that you 



* Karappeu (catarrh). 



